This invention relates to an apparatus for utilizing thermal energy for heating and cooling and more particularly to an apparatus with a plurality of individual heat pumps or reactors with multiple reactor beds and operable by sequential processing with heat transfer fluids in a plurality of processing stages and including means for simultaneously directing a plurality of the heat transfer fluids to selected groups of the reactor beds to carry out the individual processing stages with respect to each of the groups.
Heat pumps normally operate to transfer heat from a cold body to a hot body with the expenditure of energy. In the winter, heat is pumped from cold outside air into a house for space heating. In the summer, the process is reversed and heat is pumped from the air inside the house to the outside to provide space cooling.
Many heat pump systems in use require electricity as a source of energy to drive compressor units. In view of the cost of electricity and efforts at energy conservation, other heat pump systems which operate with little or no electrical input are under development.
One system of current interest involves the use of hydrogen gas in a hydride-dehydride (or hydridable material) cycle to transfer heat from one zone to another. In one portion of the cycle, heat at a high temperature is used to decompose a high temperature hydride in a reactor bed in one vessel to generate hydrogen gas to flow to a hydridable material in a separate vessel and form a low temperature hydride with the release of heat. The reactor beds are then cooled to provide conditions under which the reverse flow of hydrogen may occur. In the reverse portion of the cycle normally characterizing a heat pump operation, the low temperature hydride is decomposed using heat from a low temperature source such as outside air to generate hydrogen gas which flows to the cooled high temperature hydride reactor (composed of hydridable material). During formation of the high temperature hydride, additional heat is released at a higher temperature. The two reactors are then heated to their original temperatures to complete the cycle. This system, including variations, is disclosed in copending application Ser. No. 000,741, filed Jan. 3, 1979 now U.S. Pat. No. 4,262,739, issued Apr. 21, 1981 and titled "System for Thermal Energy Storage, Space Heating and Cooling and Power Conversion." U.S. Pat. Nos. 3,943,719 and 4,055,962 further disclose details of hydride heat pump systems utilizing the hydride-dehydride cycle.
These hydride heat pump systems have in general been designed with several separate one-bed reactors interconnected by piping and a multiplicity of valves through which hydrogen gas flows between pairs of beds. In addition, piping systems and valves are also required to direct heat transfer fluid to the various beds during each of the processing stages in the cycle. One of the problems with a system of this type is that the overall efficiency of operation is reduced by the arrangement of the separate beds and the extent of the associated piping and valves. Another problem is that the operation of the system is complex and requires extensive piping and number of valves regarding both the hydrogen portion and the heat transfer portions of the system. A further problem is that a leak of hydrogen in one part of the system requires a shutdown of other beds in the system.
One partial solution to these problems has been the development of an individual heat pump or reactor in which a tube with closed ends contains a pair of different hydrides at opposite end sections forming hydride beds. A filter is positioned intermediate the ends of the tube to prevent mixing of the hydrides while permitting flow of hydrogen gas between the beds. While this individual heat pump or reactor has the advantage that each reactor is isolated from the others, it is necessary that a system utilizing these reactors be developed.
One object of this invention is a system utilizing a plurality of individual hydride-dehydride reactors in a compact arrangement. Another object is a simplified arrangement of reactors with a reduction in the amount of piping and valves. A further object is an arrangement in which the various processing stages may be carried out simultaneously so that heat is recovered from some reactor beds while others are being regenerated. An additional object is an arrangement in which the processing stages may be carried out continuously so that as each stage in the processing is completed with respect to a reactor bed or reactor beds, heat transfer fluid for the next processing stage is directed to that bed or beds. Yet another object is an arrangement in which the cycle of operation may be repeated. Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention.